How do we use it?

Name two different items/concepts, then brainstorm the in common points between them. This can be done with similar things (like you and a friend), or really different things (like a book and chocolate).

Why its important?

It's strange to think about the similarities between two completely different things, but the challenge here lies in understanding each of these things correctly, and often leads to some truly different ideas.

Example:

Book and chocolate. 

Both can give you a lot of pleasure. 

Usually, their cover tells you what's inside. 

You need to open them to access the contents.